What is a System Boiler?

What is a System Boiler?

System boilers are installed as part of a sealed central heating system. They are a sealed circuit, system boilers aren’t exposed to atmospheric pressure. System boilers are connected to water cylinders but because the heating system is sealed, then water pressure is also maintained. They therefore eliminate the requirement for a feed and expansion system, but, unless the hot water cylinder is pressurised, still have a cold water tank. System boilers are also attractive as they are compatible with solar thermal heating, unlike combination boilers.

They are typically found in family homes and are usually cheaper and easier to install than other types of boiler because fewer heating system components mean that fitting them is neater and more efficient. In system boilers, for example, the pump is built into rather than installed away from the boiler.

Pumps in system boilers also mean that hot water is produced quickly and more economically. Expansion vessels are also built into system boilers, replacing the need for a feed/expansion tank to be installed in a loft. Safety valves, air vents and programmers are included in system boilers. So installation time is reduced considerably. Fewer materials are also required, which also reduces cost and simplifies servicing of the boiler. The closed system therefore means that they can be highly energy efficient, saving around £200 a year on the average heating bill.

Maintenance of water pressure means that system boilers are ideal for larger properties where demand for constant hot water is high. Several taps can be used simultaneously without a drop in water pressure. These types of boilers also usually large have large storage tanks, ensuring a ready supply of hot water.

They can also take up more space than combi boilers depending on the size of the cylinder. Cylinders may also heat into their surroundings unless they are extremely well insulated.